Use of dialkyl malonates in vinylidene resins



United States Patent fifice 2,859,195 Patented Nov. 4, 1958 USE OF DIALKYL MALONATES IN VINYLIDENE RESINS Robert J. Reid, Canal Fulton, William Mayo Smith, Jr., Cuyahoga Falls, and Byron H. Werner, Akron, Ohio,

assignors to The Firestone Tire & Rubber Company,-

Akron, Ohio, a corporation of Ohio No Drawing. Application February 23, 1954 Serial N0. 412,072

9 Claims. (Cl. 260-31-8) ous purposes, but the extrusion has presented various diificulties. The high temperatures necessary for processing are very close to the decomposition temperature of the composition. Therefore, it is essential that some additive be used which will lower the processing temperature below the critical range without having any undesirable effect on the products obtained.

Such resins are characterized by crystalline behavior, i. e., they fuse sharply to form relatively fluid melts. On quenching and orienting, the extruded filaments and films are crystalline in character. A syndrome of this crystalline habit is the recalcitrance of these resins to compounding: T he macromolecules of these resins prefer contact with each other and tend to reject any foreign substances such as plasticizers and the like. In the random structure obtained without orientation any added ingredient of limited compatibility, such as the processing aids of this invention, is retained in larger percentages than is possible in the stretched or oriented products. On stretching, the tendency toward exudation or spewing is considerably increased. In orienting films and filaments of vinylidene resins they are stretched to several times their original length and ordinarily until there is' a sharp rise in the modulus. It is diflicult to provide suitable processing aids which do not exhibit an undesirable spew or bloom on the surface of the oriented products and which in addition possess good heat and light stability or which at least are not detrimental to such stability.

Thus, the problem of providing processing aids for these crystalline resins is complicated not only bythe fact that they tend to reject and spew the majority of conventinal plasticizers, but, because the resins are extruded as hot melts at temperatures in the neighborhood of, for example, 170 C., many conventional resin-compounding ingredients tend to decompose or react with other compounding ingredients which are present when the resins are maintained in a molten state immediately prior to and during extrusion.

The crystalline resins to which the processing aids of and the like. For a more complete list of compounds known to copolymerizerwith vinylidene chloride to pr duce resins which can be plasticed as herein described see Krczil, Kurzes Handbuch der Polymerisationstechnik, vol. II, "Mehrstofipolymerization, Edwards Bros, Inc., p. 739, the items indented under vinylidene chloride.

The processing aids of this invention are the dialkyl malonates, the alkyl groups of which contain three to six carbon atoms. They have excellent light stability and good heat stability as well as good spew resistance. They are non-toxic, non-allergenic, and relatively odorless. In addition, they do not appreciably increase the tendency of oriented films or filaments to shrink when exposed to elevated temperatures.

Compounding and testing With regard to the use of the processing aids, a small amount in the range of 3 to 8 percent or up to 10 percent based on the weight of the. resin will generally be found most satisfactory. Less than 3 percent may be used in admixture with another processing aid. Such percentages will be stably retained within the resin in the finished oriented article. The lower membered esters show a lesser tendency to spew (greater compatibility with the resin) than the higher 'membered malonate esters. Thus, a dipropyl malonate can be used in greater amounts than a dihexyl malonate'without showing a spew tendency. about 10 percent of the processing aid be employed in a vinylidene resin because such larger amounts are incompatible and exude to the surface of oriented products produced from vinylidene polymeric resinscontaining 85 percent or more of vinylidene chloride.

The dialkyl malonates can be employed with the epoxy heat stabilizers such as glycidyl-phenylether, the mono-, di-, tri-, tetra-, and penta-chlorinated derivatives of phenoxypropene oxide, polymeric phenoxy' compounds prepared from various dihydroxy phenols and epichlorhydrin, etc. Likewise, they can be employed with light stabilizers which are esters of salicylic acid such as .phenyl salicylate, 4-tert-butylphenyl salicylate, 4-octyl phenyl salicylate, Z-methyl phenyl salicylate, 4-chloro 7 stability and may actually assist in their action.

this invention are added include both homopolymers of vinylidene chloride and copolymers thereof with not more than substantially 15 percent of other ethylenically' unsaturated compounds copolymerizable therewith. The copolymers contains at least substantially 85 percent of vinylidene chloride. Suitable comonomers for the copolymerization include, for example, vinyl chloride, vinyl fluoride, vinyl acetate, styrene acrylic and methacrylic esters such as methyl methacrylate, ethyl methacrylate and the like, acrylom'trile, vinyl-type esters and ketones such as methylvinyl ether, methylvinyl ketone and related compounds such as methylisopropenyl ketone Test data was compiled from compositions both with and without light and heat stabilizers according to the following formulation:

Parts by weight Crystalline resinous copolymer of vinylidene chloride and vinyl chloride (:15) j Glydicyl' phenyl ether Ger 2 4-t-butyl phenyl salicylate 0 01'2 Processing ai 8 The additives were ball milled'with the resin, and samples tested for heat stability, light stability and spa according to the methods given below:

Heat stability Five grams of the composition to be tested were charged into a compression mold of Hastelloy C (a 55/ 20/ 6/ 14/ 5 Ni/Mo/Fe/Cr/W alloy) in the form of a cylinder 1.25 inches in diameter. The .molding cycle was- (1) Heat for three minutes with steam at lbsJsq. in. and mold pressure of 1000 lbs./sq./in.;,

In no case will more than 3 (2) Water cool for two minutes under 1000 lbs/sq. inmold pressure; and

(3) Eject from the press. The resultant cylindrical button (1.25 inches in di- 'a'.i;'ueter and .l25.l88 inch in height) was then cut into sector-shaped specimens which were placed in a forceddraft oven .at 180 C. Specimens were removed at intervalsof 10, 20, and 30 minutes after placing in the oven, andthe behavior of the specimens on the test as a whole was rated by the operator.

Light stability One gram samples of the compositions to be tested were placed between Cellophane (regenerated cellulose) sheets ,and pressed in a flatv platen laboratory press under a total of 1000 lbs. at a temperature of 180 C., yielding a plaque approximately 6 to 8 mils thick. The plaques were tested according to the method of ASTM test D620-45T under a sunlamp for 240 hours.

Plaques were also tested in a .weatherometer for 100 hours, and 200 hours. The weatherometer was a standard X-l-A machine, using a Cor-ex D filter and operating without the sprays.

Spew rating A plaque of the compounded resin was pressed between Cellophane (regulated cellulose) sheets in a Carver press at 180 C., using aproximately 1.5 grams of resin, 10 secondpreheat, and seconds with the minimum pressure (pressure indicator just off zero). The plaque was quenched in cold water immediately and an approximately %-inch wide strip was cut from the plaque, the cellophane removed, and the strip oriented to its limit.

The oriented strips were placed in glassine bags under mild pressure so that contact of the strips with the bag was assured. Any exudation of plasticizer could then be noted as an oily streak on the glassine. Tests were carried out at room temperature and at 50 C., the latter condition tending to accentuate any migration of plasticizer.

Using the succinates of this invention, no spew was observed in this test after 56 days at room temperature. With dioctyl phthalate instead of a malonate, definite spew occurred afterone day.

Test results It was found that the use of dipropyl, dibutyl, diamyl, and dihexyl malonates do not adversely affect the heat and light stability of the resin compositions. In fact, it was often observed that the deletion of the glycidyl phenyl ether (used as, a heat stabilizer) and/or the 4-t-butyl phenyl salicylate (used as a light stabilizer) was partially compensated for by the various processing aids. Malonates in the range of dipropyl to dihexyl malonates were chosen as processing aids because these materials do not show adverse spew under the aforementioned conditions. The light and heat stability of these esters is entirely satis factory. Esters lower than dipropyl have a higher volatility and produce an odor which is slight to non-existent for the higher esters. However, esters higher than dihexyl show a markedly increased tendency to spew, and above the levels mentioned cannot be acceptably used.

The resins referred to herein are homopolymers of vinylidene chloride and copolymers thereof with up to 15 percent of other monomer copolymerized therewith. Increasing the vinyl chloride content of a resin gives polymeric products in which plasticizers generally are more compatible. The comment hereinrelative to spew is to be considered in the light of the fact that homopolymers of vinylidene chloride are somewhat less compatible with the processing aids than copolymers containing as much as 15 percent of vinyl chloride or other monomer.

Extrusions Tests were conducted using various processing aids with 4 to 8 parts'by weight of the processing aid, together with 2 parts glycidyl phenyl ether and 2 parts phenyl of processing aid on storage and possess excellent light stability when exposed to Florida sunshine. .They have good-heat stability. Difn-butyl malonate is a preferred processing aid. Extrusions carried out with conventional plasticizers such as di-octylphthalate required as least 8 parts plasticizer to give desirable extrusion characteristics and such filaments on storage in all cases exuded the plasticizer.

The processing aids of this invention lower themelt temperature of the resin, allowing extrusions to take place without decomposition. The extruded ,products are smooth and of uniform diameter, and are free of spew after orientation.

What we claim is:

1. In the process of extruding and orienting a crystalline polymeric resin selected from the group consisting of homopolymers of vinylidene chloride and copolymers thereof with up to 15 percent of other 'ethylenically unsaturated monomer, the improvement which comprises extruding and orienting the molten resin while admixed with a dialkyl malonate, as a processing aid, the malonate being in the range of dipropyl to dihexyl malonates,

whereby a non-exuding extruded, oriented product is obtained, the amountof the malonate being substantial but not in excess of about 10 percent, said percentage re ferring to percentages by Weight of the polymeric resin. 2. The process of claim 1 in which the dialkyl malonate is di-n-butyl malonate.

3. The process of claim l in which an epoxy heat stabilizer and a light stabilizerare used in the molten resin, the light stabilizer being an'ester of salicylic acid.

4. A resin composition which includes a crystalline 6. The resin composition of claim 4-which containsan epoxy heat stabilizer and a light stabilizer which is an ester of salicylic acid.

7. A resin composition which includes a copolymer; of

substantially percent vinylidene chloride and 15 percent vinyl chloride, and. a substantial amount not-inexcess of 10 percent by Weight, based on the weight of the copolymer, of a dialkyl malonate in the range .of-dipropyl' to dihexyl malonates, the nalonatebeing a processing aid for the extrusionof the resin.

8. The resin composition of claim 7 in which the proce essing aid is di-n-butyl malonate.

9. The resin composition of claim 7 which contains an epoxy heat stabilizer and a light stabilizer which is an ester of salicylic 'acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,091,241 Kvalnes Aug. 24, 1937 2,477,610 Irons Aug. 2, 1949 V 2.484.483 Be ry 0a.. 1.1. 19.49

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2359,195

' Robert J. Reid et a1;

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below a Column 1, line 7O for "vinyleitype esters" read v1nyltype ethe rs 3 column 2 line 9 after "which" insert each column 3 line 26 for "regulated" read regenerated Signed and sealed this 10th day of April 1962..

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD November 4 1958' 

4. A RESIN COMPOSITION WHICH INCLUDES A CRYSTALLINE POLYMERIC RESIN SELECTED FROM THE GROUP CONSISTING OF HOMOPOLYMERS OF VINYLIDENE CHLORIDE AND COPOLYMERS THEREOF WITH UP TO 15 PERCENT OF OTHER ETHYLENICALLY UNSATURATED MONOMER, AND AS A PROCESSING AID A DIALKYL MALONATE IN THE RANGE OF DIPROPYL TO DIHEXYL MALONATE, THE AMOUNT OF THE MALONATE BEING SUBSTANTIAL BUT NOT IN EXCESS OF ABOUT 10 PERCENT, SAID PERCENTAGES REFERRING TO PERCENTAGES BY WEIGHT OF THE POLYMERIC RESIN. 